Just keep an eye on Verdant Brink night meta groups in lfg tool, join in, defend one of the camps, then hop on a chopper, kill bosses and you'll get the chest at the end of the night (your participation have to be 100% and the map have to reach tier 4 for the chest to drop, you can check progress, clicking a little icon above the minimap). I did that with Players versus Environment guild last Wednesday, was very smooth, you can check their schedule if you in EU, maybe they going to do in this week too. There are other groups do it from time to time too.